1. Technical Field
This invention relates generally to constant velocity joints and more particularly to those which angulate and stroke in the axial direction of the joint.
2. Related Art
Constant velocity (xe2x80x9cCVxe2x80x9d) stroking joints are used in front wheel drive systems for automotive vehicles. Power is transmitted from the transmission to the drive wheels via half shaft assemblies. The shaft assemblies include CV joints at their inboard and outboard ends. The inboard CV joint is coupled to the transmission and the outboard CV joint is coupled to the drive wheels. During operation, the drive wheels move up and down and thus provision must be made for both angular and axial movement of the shaft assemblies.
FIGS. 1 and 2 illustrate a well known Rzeppa-type stroking constant velocity joint shown generally at 11. The joint 11 includes a half shaft 13 on which an inner race 15 is mounted. The inner race 15 is accommodated within an intermediate race 17. The races 15,17 are formed with a series of axially aligned curved ball grooves in which balls 19 are accommodated and restrained axially by a ball cage 21 to provide for angular pivotal movement of the inner race 15 relative to the intermediate race 17.
The intermediate race 17 is, in turn, accommodated within an outer race 23. The races 17,23 are formed with aligned axial ball channels 25,27 in which rows of ball splines 29 are received for supporting the intermediate race 17 for relative axial stroking movements relative to the outer race 23. The intermediate race 17 is fitted at its axial ends with a pair of retaining rings 18 which extend across the ball grooves to restrain the spline balls 19 against movement beyond the retaining rings 18. In operation, the intermediate race 17 is provided with a certain amount of free rolling axial stroke over which the spline balls 19 roll freely within the ball channels of the intermediate race 17. Additional axial travel of the intermediate race 17 between end stops of the outer race 23 is permitted beyond the range of free roll movement, but requires the spline balls 19 to skid or slide without rolling action along the ball channels once they confront one or the other retaining rings 18 carried on the ends of the intermediate race 17.
It is an object of the present invention to improve upon the construction and performance of such constant velocity stroking joints.
A constant velocity stroking joint assembly constructed according to a presently preferred embodiment of the invention includes an inner race, and outer race, and an intermediate race disposed between the inner and outer races which supports the inner race for angular pivotal movement relative to the outer race. At least one recirculating ball spline track is provided between the intermediate race and outer race in which a plurality of spline balls are accommodated for recirculating rolling movement in an endless path along the track to support the intermediate race for axial stroking movement relative to the outer race.
The invention has the advantage of providing a recirculating ball spline support system for the intermediate race that enables axial stroking of the intermediate race within the outer race while the free rolling spline balls circulate along the endless path of the track so as to minimize or all together eliminate the necessity for the skidding or sliding of the spline balls in order for full axial stroking of the intermediate race to take place.
The free rolling, recirculating action of the spline balls has a further advantage of decreasing the resistance to axial stroking of the intermediate race, thereby providing a smoother operating, lower noise and vibration constant velocity joint compared to joints where the ball splines skid or slide over a portion of the axial stroking of the intermediate race.
The invention has the further advantage of prolonging the operating life of such constant velocity stroking joints by minimizing or all together eliminating the skidding or sliding of the spline balls along the ball tracks. The free rolling action of the spline balls in the endless recirculating track eliminates skidding and thus wear on the balls and track.